on the science of smell and taste. he's appeared on oprah, good morning america, dateline, extra, the cbs early show, cnn and in hundreds of newspapers and magazines around the world. during the course of his pioneering research, dr. hirsch discovered the groundbreaking secret behind sensa that's changed the way the world looks at weight loss forever. >> after 25 years of research, i finally figured out why diets don't work. most diets focus on what you eat-- they have it all wrong. sensa looks at why you overeat and the biological mechanisms that prevent you from overeating. it uses the body's natural physiology to prevent you from overeating. i found that hunger isn't controlled by your stomach. it's controlled by your brain. we don't overeat just because we're hungry. it's because we love to eat. and diets don't stop you from wanting to eat, they just stop you from eating what you want, and that's a recipe for failure. >> the fact that the brain can figure this out before the stomach... that, to me, was fascinating, and that attracted me further, as i think it should a lot of doctors. >> dr.